It is proposed to infect rat gingival tissue with cell wall fragments isolated from group A streptococci, group D streptococci and selected oral streptococci. The main aim is to refine and extend the rat model of human disease, with particular emphasis placed on the bone resorbing capabilities of the inflammatory process. It is also planned to develop sensitive and reliable assays for cell-mediated and humoral immune responses in the injected animals. Differences in the biological properties of the various cell wall material will be associated with structural differences in the peptidoglycan-poly-saccharide complex. BIBLIOGRAPHIC REFERENCE: Schwab, J.H. and R. Smialowicz. 1975. Interaction of bacterial cell wall polymers and rat macrophages. Z. Immun. Forsch. 149:283-288.